Got my pipe and found My mixture got better. Went form oily black to gray on my spark plug. I think that your mixture should be the same its just that the quantity has increased. like a supercharger you are effectively increasing the size of the combustion chamber, More air gas same ratio as before.

Every engine and situation is different. Jetting depends on a lot of things, pipe, carb, fuel/oil ratio, altitude, porting, plug etc. Most of our customers don't need to rejet or if they do adjusting just the needle will get them close enough.

I had to move my jet needle clip one notch down from the center notch (to richen it slightly). I'm getting a nice tan color on my plug now. With the stock exhaust and the jet needle clip set on the center notch, my plug was always black.